HK3A Carb Service info

[tfb3]

Have the above on a 150 Auto. Used a Tillotson OEM RK 36HK kit on the carb, the saw will not idle but will run while engaging finger throttle. Set H and L at 1 turn also tried 1 1/2 and 1 1/8 still no dice.  seems like when i adjust the idle screw it does not make any difference. Do not see any other serviceable parts.  Removed needles they seem ok.  Hard to find any info on this 3A not sure what changes were made if any once replaced.  Have ordered a used Homelite carb to replace it. still like to find out why it will not work.  Do I need to change anything else out to use the other carb?  

[sweepleader]

If you can get it to run with the throttle held open using the trigger, you should be able to set the idle speed up enough to get the engine to run on the main jet system without holding the trigger. The idle speed screw does the same thing as the trigger. Once you have it running with the idle set way up, reduce the idle screw some and adjust the idle mixture to try to get the speed up as fast as it will go. Then reduce the idle speed screw again and re-adjust the idle mixture for max speed again. Repeat this until the idle speed is low enough to get the clutch to release and the chain to stop. This is the only procedure I use when I have trouble getting the idle mixture set correctly.

Once the saw will idle using the above, try the trigger for acceleration to cutting speed. If the saw stumbles on acceleration, I open the idle mixture screw 1/8 of a turn or so and try again until the saw will accelerate smoothly. Richening the idle mixture is the correct method to get proper acceleration performance.

When this is done, it's time to recheck the high speed and be sure it is on the rich side. The engine should sound rough until the chain is in a cut at which point is should smooth out and run with max power.

This whole thing only takes a couple minutes if the carb is OK, if this does not work, I start looking for air leaks or plugged passages in the carb. The screws in the picture look serviceable but there may be damage to their seats in the carb. If they have been tightened too much, metal can be swaged into the jet closing it up some and making adjustment to the rich side impossible, that would mean it's new carb time.

[tfb3]

Thanks, I had it on off the saw over 8 times may tackle that advise on a snow day! Was time to walk away!

[makromer]

Dec 12, 2020 14:55:19 GMT -5 tfb3 said:

Thanks, I had it on off the saw over 8 times may tackle that advise on a snow day! Was time to walk away!      WHERE did you find a replacement carb.  My 150 has a Walbro HDC #3.  No parts available that I can find.  I see that the Tillotson will fit.  Thanks for your help